It's a charm-off! Robert Downey Jr. stopped by Castle for a quick exchange of banter between the man himself, Nathan Fillion. Alas, the whole thing didn't go much further than, "I'm Iron Man, fuck off! That's a wrap everybody!"

But instead of seeing this plug for what it really is — a quickie commercial for The Avengers directly aimed at all the families enraptured by Fillion's roguish good looks — we're going to view this as a secret wink of what's to come in the Marvel movie world. Thus confirming that Fillion has landed the part for Henry Pym in the bag. Clearly that's exactly what's happening right here.

Besides that, this episode held the infamous Firefly reunion starring Adam Baldwin. And yes, there was much quipping to be had. Did everyone shriek a little when they started passing around a brown coat? When will it be Alan Tudyk's turn?